Texture Of Cooked Rice Research Articles

Grain Quality Evaluation of Several Upland Rice Varieties in Indonesia

Abstract High-yielding rice varieties that are adaptive to dry land conditions are the main technological component in efforts to increase rice production also known as upland rice. This study aimed to determine the physical quality, milling quality, physicochemical characteristics, and sensory test of six upland rice new superior varieties namely Inpago 8, Inpago 10, Inpago 12, Inpago Unsoed, Rindang 1 and Rindang 2. The quality analysis was carried out at Rice Quality Laboratory, Indonesian Center for Rice Research (ICRR) in Sukamandi, West Java, Indonesia. Furthermore, rice quality data is compared with the Indonesian National Standard (INS) for paddy No. 0224-1987/SPI-TAN / 01/01/1993 and with INS of rice No 6128:2020. The result showed that upland rice varieties have the criteria of the third class of INS paddy. Out of six varieties, four varieties were categorized as long rice and the rest were medium rice (Inpago 8 and Inpago Unsoed). All varieties were classified as medium shape. According to milling quality, Inpago 12 followed by Inpago 8 has the best yield of brown rice. Meanwhile, the best yield of milled rice was Inpago 12 followed by Inpago 10. All varieties met the percentage of head rice (maximum 75%) and broken rice (maximum 22%) for the second medium class. The Inpago 8, Inpago 10, Inpago 12, and Inpago Unsoed varieties belong to the low to medium amylose group, having a medium gel consistency with a separated and fluffy cooked rice texture character. According to the sensory test findings for cooked rice, there were no differences among any of the kinds in terms of flavor, color, shine, taste and overall evaluation. Based on physical, milling quality and physicochemical characteristics, Inpago 12 is the best variety of all the upland varieties observed.

Experimental Warming Increased Cooked Rice Stickiness and Rice Thermal Stability in Three Major Chinese Rice Cropping Systems.

Climate warming is a critical environmental issue affecting rice production. However, its effects on cooked rice texture and rice thermal properties remain unstudied in China. To address this gap, we conducted a two-year multi-site field warming experiment using free-air temperature increase facilities across three major Chinese rice cropping systems. Interestingly, warming had a minimal impact on the hardness of cooked rice, while it significantly increased stickiness by an average of 16.3% under warming conditions. Moreover, compared to control treatments, rice flour exhibited a significant increase in gelatinization enthalpy, onset, peak, and conclusion temperatures under warming conditions, with average increments of 8.7%, 1.00 °C, 1.05 °C, and 1.17 °C, respectively. In addition, warming significantly declined the amylose content, remarkedly elevated the protein content and relative crystallinity, and altered the weight distribution of the debranched starch. Correlation analysis revealed significant relationships between cooked rice stickiness, rice flour thermal properties, amylose content, protein content, and partial starch structures. Therefore, warming-induced alterations in rice composition and starch structure collectively enhanced cooked rice stickiness and rice thermal stability.

Relationships between texture properties of cooked rice with grain amylose and protein content in high eating quality indica rice

AbstractBackground and ObjectiveTexture is critical in determining the eating quality of cooked rice and is dependent on physiochemical properties of rice grains. In this study, relationships between texture properties of cooked rice with grain amylose and protein content were evaluated across 25 high eating quality indica rice varieties.FindingsGrain amylose and protein content ranged from 13.2% to 20.0% and from 5.37% to 7.77%, with means of 17.6% and 6.43%, respectively. The ranges of hardness, springiness, cohesiveness, resilience, and chewiness of cooked rice were 425–1074 g, 0.672–0.812, 0.447–0.632, 0.278–0.457, and 130–480 g, with means of 710 g, 0.768, 0.570, 0.394, and 320 g, respectively. Correlation plot analysis and partial correlation analysis showed that all five texture properties of cooked rice were significantly related to grain amylose content, whereas the relationships between each of the five texture properties and grain protein content were not significant or much less significant than the relationships between texture properties and grain amylose content.ConclusionsHigh eating quality indica rice varieties have diverse texture properties when cooked. Selection of texture properties of cooked rice should focus on grain amylose content rather than grain protein content for high eating quality indica rice.Significance and NoveltyThis study identifies the critical physiochemical property determining cooked rice texture in high eating quality indica rice.

Importance of both leached and residual starch molecular structures in determining cooked rice texture at different rice-to-water cooking ratios

Although texture of cooked rice has been investigated with regard to its relation to starch structure, it remains unclear how starch molecular structure and water content together affect its texture. Thus, the texture, and starch molecular structure of 10 rice varieties and their leachates during cooking were studied with a range of rice-to-water ratios. Although hardness of cooked rice decreased, no trend for the alteration of stickiness observed over the increase of water content. Generally, more amylopectin with DP 12–36 and amylose with DP 5000–20,000 in leachate, less starch molecules with DP > 36 in residual materials resulted in a higher stickiness of cooked rice, which is rationalized by their slower retrogradation tendency and higher amount of non-reducing ends available for binding to textural probe. Rice-to-water ratio was another crucial factor in determining relations between starch structures and cooked rice texture. For example, more leached amylopectin with DP 12–100 resulted in a higher stickiness of cooked rice, while this was not the case for rice cooked at rice-to-water ratios of 1: 1.2 and 1: 1.4. These results give new insights on the effects of starch molecular structure and water content on the cooked rice texture.

Long-term straw return improves cooked indica rice texture by altering starch structural, physicochemical properties in South China

Straw return can improve rice eating quality by modifying starch formation from long-term field trials, whereas the relevant mechanisms are still unknown. A long-term field experiment, including straw removal (CK), straw burning return (SBR), and straw return (SR) was conducted to investigate the starch structure, physicochemical properties, and cooked rice textures of indica early- and late-rice. Compared with CK, SBR and SR enhanced relative crystallinity, amylopectin long chains in both rice seasons, and gelatinization temperatures in late rice. Compared to SBR, SR decreased protein content and amylopectin short chains but increased starch branching degree, breakdown, and stickiness, ultimately contributing to improved starch thermal and pasting properties. Meanwhile, SR decreased hardness, cohesiveness, and chewiness, resulting in cooked texture meliorated, which was mainly attributed to amylopectin chain length and starch granule size. The results suggest that SR increased cooked texture of indica rice by altering starch structural and physicochemical properties.

Starch multiscale structure and physicochemical property alterations in high-quality indica rice quality and cooked rice texture under different nitrogen panicle fertilizer applications

The starch multiscale structure, physiochemical properties, grain quality and cooked rice texture of high-quality early and late indica were analyzed under nitrogen panicle fertilizer (low panicle fertilizer, LPF; middle panicle fertilizer, MPF; high panicle fertilizer, HPF) treatments and their internal relations were investigated. Compared to the MPF treatment, the starch granules in HPF and LPF had more surface-proteins and irregular voids for high-quality early and late indica rice cultivars, respectively. Nitrogen panicle fertilization application increased amylopectin medium and long chains as well as protein content, resulting in higher relative crystallinity and gelatinization temperatures. Moderate changes in starch multistructures and physicochemical properties such as branching degree, amylopectin medium chain, and pasting viscosities derived from MPF treatment significantly improved processing, appearance qualities and cooked rice texture. Additionally, the decrease in starch branching, gelatinization temperatures, and granule uniformity along with an increase in large granules, breakdown, and △Hgel under MPF treatment were the main reasons for improving rice textural properties.

The Effects of Genotype × Environment on Physicochemical and Sensory Properties and Differences of Volatile Organic Compounds of Three Rice Types (Oryza sativa L.).

Understanding the effects of genotype, environment and their interactions on rice quality is of great importance for rice breeding and cultivation. In this study, six rice varieties with two indica, two japonica and two indica-japonica types of rice were selected and planted at ten locations in Zhejiang Province to investigate the genotype (G) × environment (E) on physicochemical and sensory properties and the differences of volatile organic compounds (VOCs) among the three types of rice. Analysis of variances showed that apparent amylose content (AC), total protein content (PC), alkali spreading value (ASV), RVA profiles, and appearance (ACR), palatability (PCR), and sensory evaluation value (SEV) of cooked rice and texture of cooled cooked rice (TCCR) were mainly affected by genotypic variation, whereas the smell of cooked rice (SCR) was mainly affected by environment (p < 0.05). The G × E effect was significant for most parameters. The weather in the middle and late periods of filling had important effects on the formation of rice quality, especially on setback (SB) and pasting temperature (PT) (p < 0.01). They were negatively correlated with the texture of cooked rice (TCR) and SEV (p < 0.05). Peak viscosity (PV) and breakdown (BD) were positively related to the sensory evaluation parameters (p < 0.01) and could be used to predict cooked rice quality. A total of 59 VOCs were detected, and indica, japonica and indica-japonica had 9, 6 and 19 characteristic compounds, respectively. The principal component analysis showed that the physicochemical and sensory properties and VOCs of indica-japonica rice were more stable than those of indica and japonica rice at ten locations in Zhejiang Province. It is helpful for rice breeders to understand how the environment affects the physicochemical, sensory properties and VOCs of the three rice types, and it is also important for food enterprises to provide rice products with stable quality.

Mutual Relations between Texture and Aroma of Cooked Rice-A Pilot Study.

Texture and aroma are two important attributes for the eating quality of cooked rice, but their mutual relations are not clear. Cooked rice with a desirable texture might suffer from a deteriorated aroma property. To better understand the relations between texture and aroma, six different rice varieties with desirable eating qualities have been selected, with their texture and aroma profile characterized by a texture analyzer and gas chromatography-ion mobility spectrometry, respectively. A large variance of textural attributes and a total number of 39 major volatile organic components were observed for these cooked rice varieties. Pearson correlation showed that the hardness of cooked rice was positively correlated with the content of E-2-hexenal, 2-hexanol-monomer, 1-propanol, and E-2-pentenal, while stickiness was positively correlated with 5-methyl-2-furanmethanol and dimethyl trisulfide. Possible underneath mechanisms were discussed for these relations. These results could help the rice industry to develop rice products with both desirable texture and aroma property.

Relation of cooked rice texture to starch structure and physicochemical properties under different nitrogen managements

Nitrogen management, especially panicle nitrogen fertilization (PNF), can affect cooked rice textures by altering starch quality, but the details are unclear. In this study, the starch multi-level structures, physicochemical properties and cooked rice textures of indica under different nitrogen managements were analysed and their internal relations were investigated. With an increase in PNF, large granules, amylopectin short chains, amylose content, thermal temperatures, setback, and hardness first exhibited decreasing trends and then increasing trends, which were relatively lower under moderate PNF (N3), whereas α-1,6 linkage, relative crystallinity, protein content, enthalpy of gelatinization (△Hgel), peak viscosity, breakdown and stickiness exhibited the opposite trends. N3 treatment significantly increased △Hgel and breakdown and decreased setback, hardness and chewiness, suggesting that it might contribute to better starch thermal stability and pasting properties, ultimately improving cooked rice texture. Nitrogen management affected the texture of cooked rice mainly by improving starch multi-level structures, thermal and pasting viscosities.

Understanding the Influences of Rice Starch Fine Structure and Protein Content on Cooked Rice Texture

AbstractAmylose content, fine structure, and protein content affect the hardness and stickiness of cooked rice. However, the mechanisms of those effects have not been fully understood especially the fine structure of amylose. Here, 22 rice varieties with large ranges of both starch chain‐length distributions and protein content are examined, and the starch structural results are parameterized using biosynthesis‐based models. The ratios of the activities of branching enzyme and starch synthase for amylose showed positive and negative correlations with rice hardness (coefficient 0.556 and 0.838) and stickiness (coefficient −0.498 and −0.639), respectively. Protein content is strongly positively correlated with hardness, with nitrogen application up to the panicle development stage (coefficient 0.640). New findings could be obtained from these correlations, which reveal that in the whole region of amylose, the shorter the amylose is, the harder and less sticky the cooked rice is, which has not been reported previously. In addition, protein is found to influence rice hardness significantly, while rice stickiness is less affected by it. Therefore, a comprehensive mechanism of protein effects on rice texture is proposed. This work provides information for breeders to develop improved rice varieties.

Effects of warming on starch structure, rice flour pasting property, and cooked rice texture in a double rice cropping system

AbstractBackground and objectivesClimate warming has significant effects on rice quality. However, the effects of warming on starch structure, rice flour pasting properties, and cooked rice texture are unclear in double rice cropping systems. Therefore, a free‐air temperature increase experiment was conducted with two indica rice cultivars. The objectives of this study were to explore the changes in rice flour pasting properties and cooked rice texture under warming conditions and their relationships with starch structures.FindingsUnder warming conditions, rice starch had a lower amylose content (Peak 3) and proportion of long amylopectin branch chains (B3 chains) but a higher proportion of short amylopectin branch chains (A chains and B1 chains), amylopectin branching degree, relative crystallinity, ratio of 1045/1022 cm−1, and swelling power. Compared to the control treatment, warming significantly increased the peak viscosity, breakdown, and pasting temperature but decreased the setback of rice flour. Moreover, the hardness of cooked rice was significantly decreased, while its stickiness was significantly increased under warming conditions.ConclusionsThe changes in starch molecular structures resulted in lower hardness and setback but a higher stickiness, peak viscosity, breakdown, and pasting temperature of cooked rice or rice flour, which means better eating quality and worse cooking quality of double‐cropped indica rice under climate warming conditions.Significance and noveltyThese findings are expected to provide important information for improving rice cooking and eating quality and developing the rice industry under future climate warming conditions.

High Resistant Starch Rice: Variation in Starch Related SNPs, and Functional, and Sensory Properties.

Human diets containing greater resistant starch (RS) are associated with superior glycemic control. Although high amylose rice has higher RS (29 g/kg to 44 g/kg) than lower amylose content varieties, sensory and processing properties associated with RS have not been evaluated. This study used variants of Waxy and starch synthase II a (SSIIa) genes to divide high amylose (256 g/kg to 284 g/kg) varieties into three haplotypes to examine their effects on RS, RVA parameters, and 14 cooked rice texture properties. RVA characteristics were influenced by both genes with peak and hotpaste viscosity differentiating the three haplotypes. Setback from hotpaste viscosity was the only RVA parameter correlated with RS content across three haplotypes (r = −0.76 to −0.93). Cooked rice texture attributes were impacted more by Waxy than by SSIIa with initial starch coating, roughness, and intact particles differentiating the three haplotypes. Pairwise correlation (r = 0.46) and PCA analyses suggested that roughness was the only texture attribute associated with RS content; while protein content influenced roughness (r = 0.49) and stickiness between grains (r = 0.45). In conclusion, variation exists among genetic haplotypes with high RS for sensory traits that will appeal to diverse consumers across the globe with limited concern for negatively affecting grain processing quality.

Effect of Cold Plasma Treatment on Cooking, Thermomechanical and Surface Structural Properties of Chinese Milled Rice

Cold plasma (CP) treatment for enhancing functional and cooking properties has been investigated on less rice varieties and delays the industrial adoption of this technology. This study treated three types (short-, medium-, and long-kernel) of milled rice from six Chinese varieties with helium plasma (Radio frequency, 13.56 MHz, 140 Pa) at a combination of watt and time, and evaluated the cooking properties, cooked rice texture, kernel appearance quality, and surface morphology, as well as flour thermal and thermomechanical properties. CP treatment at 120 W for 20 s significantly decreased the cooking time and the hardness of cooked rice while increasing adhesiveness, elasticity, and gruel solid loss. CP did not significantly change the appearance of milled rice, except for chalky rice rate, and kept the peak temperature and enthalpy of gelatinization in rice flour. 120W–20s CP significantly increased rice dough development and stability time, starch gelatinization maximum torque, and starch breakdown, but decreased the stability of protein network and starch retrogradation. As CP power strength increased from 120 to 520 W; the surface rupture of a rice kernel became more severe, and small particles aggregated on the rough surface. Compared with the 0 h sample of 120W–20s CP treatment, the repeating CP treatments at 24 h, 48 h, and 30 d significantly decreased water contact angle and free fatty acid content, but increased water absorption rate and chalky rice rate. These results suggest that 120W–20s helium CP improved the cooking properties of milled rice via leading to the rough kernel surface, higher water absorption rate, weak protein network, and a higher speed of starch gelatinization.

Analysis of apparent amylose content of market milled rice via digital image photometry using a smartphone camera

Apparent amylose content (AC) of market milled rice was analyzed through digital image photometry (DIP) utilizing a smartphone camera and a free-access software (ImageJ). The DIP-AC method was validated using seven test samples and applied to a set of 17 commercially available milled rices varying in AC. A light box was constructed to accommodate a cuvette and a smartphone while ImageJ was used for digital image analysis towards quantifying AC. Smartphone camera settings were also optimized using the red, green, and blue (RGB) values of the digital images of amylose-iodine blue solutions. ISO 100 combined with shutter speed 1/640 was the optimum and most suitable settings combination when B values were used to generate calibration curves yielding a high degree of linearity (r = 0.995–0.998). Validation showed the DIP-AC method to be accurate based on the conventional ultraviolet–visible (UV-vis) spectrophotometric AC assay. It was also found to be repeatable and precise for non-waxy rice samples only, yielding RSD values below 7% among all replications made within one day and across different days. With the optimized DIP-AC assay, limits of detection and quantitation of AC that is capable of iodine binding at alkaline pH and influencing cooked rice texture, were 0.2% and 0.4% (milled rice basis at 12–14% moisture), respectively. The reported DIP-AC method can be a reliable and accurate assay for determining AC of non-waxy milled rice alternative to UV–vis spectrophotometry. Further refinement of the DIP-AC method is warranted to improve precision in measuring AC of milled waxy rice.

Water-absorption characteristics and cooked rice texture of milled rice

Water-absorption characteristics and cooked rice texture of milled rice

Causal relations among starch chain-length distributions, short-term retrogradation and cooked rice texture

Rice is cooked and consumed after a short-term cooling which is associated with the short-term starch retrogradation. The two most important textural attributes (hardness & stickiness) of 28 cooked rice varieties were investigated in this study, based on the causal relations between starch chain-length distributions (CLD) and short-term retrogradation properties. Size-exclusion chromatography (SEC) was used to characterize the starch CLD, while the setback viscosity (SBV) from rapid visco-analyzer and hydrogel firmness (HF) from textural profile analyzer were represented as characteristics of the short-term retrogradation process. Pearson correlations showed that regardless of amylose content, rice starches containing relatively shorter amylose molecules with short to long chains, and more amylopectin medium and long chains with the degree of polymerization (DP) > 69 can all promote the short-term retrogradation rate, resulting in cooked rice with a hard and non-sticky texture. It also suggests that both SBV and HF could be utilized to predict the final cooked rice texture such as the hardness and stickiness. Furthermore, rice starches with a relatively higher amount of medium chains but less short chains within the amylopectin molecules are related to a less sticky texture of the cooked rice. The current study provides important information for rice industry and breeding programs to develop new varieties with targeted eating qualities.

The Volatile Components and Rice Quality of Three Indonesian Aromatics Local Paddy

The purpose of this research was to study the post-harvest analysis of local aromatic rice variety of AnakDaro, CicihMerah, and Mandoti covering the volatile component, physical and milling quality, and the physicochemical properties of rice. The research materials were obtained from local farmer in West Sumatera, South Sulawesi, and Bali. The analysis was conducted at the Rice Quality Laboratory at Indonesian Center for Rice Research (ICRR), Sukamandi, West Java. The results indicated that AnakDaro was extracted with Likens- Nickerson had a 2-acetyl-1-pyrroline amount (13.79 ppb) higher than that of Mandoti and CicihMerah. The extraction technique with Likens Nickerson has the best recovery compared to SPME (Solid Phase Microextraction) and maceration. In general there are differences in physical quality of grain and rice, milled quality and rice protein content of AnakDaro, Mandoti and CicihMerah. AnakDaro had high amylose content and hard cooked rice texture in cold conditions. CicihMerah had high amylose content with soft cooked rice texture in cold conditions. Mandoti had a very low amylose content with a very soft cooked rice texture in cold conditions. The characteristic of gelatinization temperature of Anak Daro and CicihMerah were high (> 74°C) while Mandoti was moderate (70-74°C).

Differences in starch structure, thermal properties, and texture characteristics of rice from main stem and tiller panicles

The physicochemical properties of grains from main stem and tiller panicles are primarily responsible for the overall quality of rice. Thus, in this study, we report our findings on the starch structure, thermal properties, and cooked rice texture of main stem and tiller panicles from three Japonica rice varieties. Compared to main stem panicle, rice grains from tiller panicles had inferior processing and appearance qualities. Starch from tiller panicles had a lower apparent amylose content (AAC), lower average degree of polymerization (DP) and long-chain (DP ≥ 37) content in amylopectin, while the proportion of amylopectin fractions, fa (DP 6–12) and fb2 (DP 25–36), increased; this resulted in a higher swelling power, water solubility, lower gelatinization temperature and retrogradation. Although there was no change in starch crystal type between the main stem and tiller panicles, grains from tiller panicles had a higher relative crystallinity. While grains from tiller panicles had a lower hardness after cooking, stickiness conversely increased. Overall, the results suggest that grains from tiller particles, particularly late-initiated panicles, have lower grain processing and appearance qualities; however, the resultant physicochemical properties of the starch lead to improved thermal properties and higher quality of cooked rice. The results from this study will aid in efforts directed towards improving cooked rice quality.

Impact of alternative irrigation practices on rice quality

AbstractBackground and objectivesCurrent global concerns about water scarcity present a need to investigate more water‐efficient rice production methods. Alternate wetting and drying (AWD) is fast emerging as a water‐saving irrigation practice, but its effects on rice quality are largely unknown. To ascertain the impact of water‐saving irrigation practices on rice quality, three irrigation treatments, namely continuous flooding with cascade delivery (four fields); continuous flooding with multiple‐inlet delivery (four fields); and AWD with multiple‐inlet delivery (four fields), were established on 12 production‐sized (16.2 ha) fields in 2017.FindingsResults of rice quality evaluations showed that irrigation treatment had a significant (p &lt; 0.05) effect on chalkiness. Samples harvested from the AWD fields had slightly greater mean chalkiness (5.6%) than samples harvested from the two continuously flooded fields (5.1–5.2%). Milling yields were not affected (p &gt; 0.05) by irrigation treatments. The average milled rice and head rice yields across irrigation treatments were 73% and 59%, respectively. Regarding pasting properties, while peak and breakdown viscosities were not affected (p &gt; 0.05) by the irrigation treatments, setback viscosity (SB), which is often linked with cooked rice texture, was impacted. Among the irrigation treatments, mean SB was least for the AWD treatment (146 cP), while the mean SB for the continuously flooded fields was similar at 168–169 cP.ConclusionsIn summary, the use of AWD with multiple‐inlet delivery did not impact milling yields of rice relative to the conventional practices of continuous flooding. However, rice harvested from the AWD treatment fields had slightly greater chalkiness and lesser SB.Significance and noveltyThis study addresses a gap in literature concerning the impact of emerging water‐saving irrigation techniques, especially AWD as it involves subjecting rice to a certain level of water stress, on rice grain quality characteristics.

High-amylose rice: Starch molecular structural features controlling cooked rice texture and preference

Cooked high-amylose rices have slower digestibility, giving nutritional benefits, but inferior eating qualities. Molecular structural mechanisms for this inferior eating quality are found here using structural analysis by size-exclusion chromatography of both the parent starch and starch leached during cooking. All commonly-accepted sensory attributes of cooked rice were characterized by a trained human panel. Hardness, with the strongest negative correlation with panelist preference, was the dominant but not sole factor determining palatability. Hardness was controlled by the amounts of medium and long amylopectin chains and amylose in the starch, and by amylose content and amount of longer amylopectin chains in the leachate. This gives knowledge and understanding of the molecular structural characteristics of starch controlling cooked-rice preference: not just high amylose but also other aspects of molecular structure. This can help rice breeders to target starch-synthesis genes to select slowly digested (healthier) rices with acceptable palatability.